Significance of zoledronic acid in the adjuvant therapy in patients with breast cancer

Introduction. Zoledronic acid is a medicine belonging to the bisphosphonate group. Its action is to inhibit the function of osteoclasts, which leads to a reduction in bone resorption. This preparation has a proven effect in the treatment of osteoporosis and Paget’s disease. Bisphosphonates have also found use in the treatment of breast cancer. Studies conducted for many years indicate that zoledronic acid works most favorably in combination with adjuvant therapy. Breast cancer patients who are postmenopausal and being treated with chemotherapy are at risk of bone mass loss and hypercalcemia. Bisphosphonates effectively manage this. In addition, zoledronic acid indirectly exerts anticancer effects by modulating the immune system. All this allows us to conclude that taking this drug reduces the risk of bone metastasis in breast cancer patients. Dosage is also key in all this. There are several regimens offered to osteoporosis and breast cancer patients. So far, the following have been studied: conventional dosing (4 mg IV every 3-4 weeks), maintenance dosing (4 mg IV every 3-6 months) and metronomic dosing (1 mg IV weekly). It cannot be ruled out that each of these regimens may have a different antitumor effect. By reviewing scientific works, we aim to present the treatment options with zoledronic acid for breast cancer patients. We will describe the impact on their results depending on the dosage and we will present the other side of the coin, which are the side effects of taking this preparation. Aim. This review provides an overview of the effects and impact of zoledronic acid in adjuvant therapy in patients with breast cancer. Material and methods. The article presents the current state of knowledge on zoledronic acid as an adjuvant treatment option in breast cancer patients. It is a detailed literature review using Google Scholar, PubMed and Journal of Education Health and Sport platforms. Publications using the following key words were analyzed: bisphosphonates, zoledronic acid, osteoporosis, breast cancer, bone metastases. Conclusion. Women diagnosed with breast cancer should be treated in a multidisciplinary manner. We treat early detected cancers to achieve complete remission. Long-term survival is our primary goal, and in pursuing it we should consider the potential impact of this treatment on the patient’s skeletal system. Clinical studies allow us to conclude that there is a correlation between the initiation of antiresorptive therapy at an early stage of cancer and overall survival. Additionally, zoledronic acid significantly reduced the number of fractures. The collected data allow us to conclude that the addition of zoledronic acid to the established treatment regimens has a potentially positive effect on the group of postmenopausal patients undergoing tamoxifen treatment or with existing bone metastases. Keywords: bisphosphonates, zoledronic acid, breast cancer, osteoporosis, bone metastases.